Treatment of artificial leather sheetings and product of same



R. B. HILL. ET AL Emme I4, E932.

TREATMENT OF ARTIFICIAL LEATHER SHEETINGS AND PRODUCT OF' SAME Filed April 27, 1929 Patented `lune 14, 1932 IUNITED STATS PATENT OFFICE ROGER B. HILL, OF BERLIN, NEW HAMPSHIRE, AND JOHN A. FOGARTY, OF PORTLAND,

MAINE, ASSIGNORS T BROWN COMPANY, 0F BERLIN, NEW HAMPSHIRE, A COR- PORATION OF MAINE TREATMENT 0F ARTIFICIAL LEATHER'SHEETINGS AND PRODUCT OF SAME Application mea april 27,

In the manufacture of artificial leather Sheeti'ngs,'it is sometimes the practice'to 1mpregnate fibrous sheet material such as textile fabrics, felts, and,` papers with aqueous Y making type, it has been found capable of absorblng a comparatively large amount of dispersed rubber and that the impregnated and dried product has characteristics including strength, stretch, resistance to tear, water repelancy, plability, and feel simulating those of natural leathers. The degree i to which these characteristics are acquired by the product depends upon the particular i conditions of its manufacture, but it has been found possible to produce artificial leather sheetings asdescribed, eminently suitable for use as a substitute of the natural product in various fields.

Artificial leather sheetings of the type described, whether or not the rubber is vulcanized, are commonly characterized by a harsh and sti feel, comparable to that sometimes i possessed by the natural product. For some.

fie

commercial uses, harshness and stiffness is decidedly disadvntageous, but the problem of doing away with these characteristics cannot be solved successfully, so far as we are aware by modifying the characteristics of the rubber as by compounding therewith various softening or plasticizing agents such as oils or waxes, (as, generally speaking, if a sufticient amount of such agents be used to cause a decided softening, the strength of the artificial leather sheeting is seriously impaired.

We have found that if artificial leather sheetings, suchl as hereinbefore described, are mechanically worked While wet, preferably by stretching, and then dried, they are made remarkably exible or pliable and at the same time improved in strength, stretch and tear resistance. Such a treatment may be carried 1929. serial no. 358,745.

.out successfully by wetting the sheeting With either cold or with hot water, to'produce products which differ somewhat in their characteristics, the hot Water wetting treatment, for instance, tending to give more flexible products but which have a distinctly rubbery feel. We have further found that the method described'may be advantageously practiced where it is desired to incorporate water-soluble materials into the artificial leather sheeting. For instance, if it is desired to color the sheeting, a water-soluble dyestuff may be present in thel wetting water, in which case dyeing and softening of the sheeting may be eected at the same time, mechanical working of the wet sheeting resulting in an even distribution of color through the product. We have still further found that for many purposes it is desirable to add a tanning agent to the wetting Water, particularly when the method is carried out with hot water and the dispersed rubber used as a raw material in making the artificial leather sheeting is an unpurified rubber latex in the sense thatY it contains proteins, resins, and other nonrubber constituents associated with natural latex, as in such case they artificial leather sheeting may be somewhat tacky. The addition of 1% to 2% of a tanning agent, preferably a vegetable extract such aschestnut, oak, or quebracho, to the water results in a product with a dry feel, and it is believed that the product is improved in stability or resistancek to ageing. While tanning agents of vegetable origin are preferable in that they not only impart color and odor characteristic of vegetable-tanned hides and skins to the product, substantially removin the characteristic rubber odor, but also mo ify the characteristics of the rubber in the sheeting so that an improvement in quality of product is realized. ln lieu of vegetable tanning agents,

it is possible to use alum or other inorganic tanning agents. The action of the tanning agents, it is believed, is to convert the albuminous materials in the sheeting to insoluble condition, so that they no longer are subject to putrefaction, or deterioration, by ageing.l ln conformity with this theory, it is found that if a sheet of interfelted fibers is impreghated with a. iaax purified in the sans@ that proteins, resins, and other non-rubber constituents associated with natural latex have been removed therefrom, there is little or no 'and an additional local stretching.

On the accompanying drawing, Figure l represents more or less diagrammaticallyand conventionally an apparatus for carrying out the method of the present invention.

Figure 2 is a plan view of a roll capable of effecting sidewise stretching of the sheeting when the latter is passed in tight contact therewith in the direction indicated.

Figure 3 is a front view, partly in section, of-4 a air of rolls designed vto effect local stretching of the sheeting.

Referring to Figure 1 of the drawing, at l is shown a roll of sheeting S, which may comprise a base of interfelted cellulose fibers which has been impregnated with rubber, as by dipping in rubber latex and then drying. The sheeting S may be unwound from the roll l and passed into a bath of water 2, in which guide rolls arranged in a lower series a and an upper series b, may be maintained submerged, the sheeting passing alternately from a lower roll to an upper roll to furnish a large area of contact with the water, and thus to permit the sheeting to become thoroughly wetted and contain, say, from onehalf to twice its own weight in water by the time it passes out from the bath. The wa ter bath may be at room temperature, but, if desired, it may be hot'. It may be desirable to add tanning agents o'r other water-soluble materials such as dyestuffs thereto. The water-soaked sheeting, emerging from the bath ma be passed through a` series of pairs of rolls indicated at AB, and C, these rolls preferably being covered with softqrubber so that gentle squeezing is effected when the sheetin passes therethrou h. The rolls of each pair may be driven at t e same peripheral speed in order to avoid rubbing action and bruising of the faces of the sheet, but the rolls B should be driven a little faster than the rolls A, and the rolls AC a little faster than the rolls B, so as to eifect longitudinalstretching of the sheeting throughout its body portion between the regions engaged by the successive pairs of rolls. Between the rolls A and B and B and C are preferably mounted rolls D and E having herringbone-ribbed surfaces h, so that Vas the tensionedI sheet passes thereover in tight contact with the herringbone ribs and in the direction indicated in Figure 2, lateral stretching of the sheeting is effected. The rolls D and E need not be positively driven, their,l rotation being effected by frictional engagement with the wet sheeting. The stretched wet sheeting may then be passed over a dryer drum 3 and the dried sheeting wound on a roll 4 from which it may be taken for suitable finishing treatment. In lieu of using' rolls as illustrated in Figure l, successive pairs of rolls such as shown in Figure 3 may be used, each roll of a pair being provided with rows of spaced blunt pegs p projecting from its surface and cooperating with the spaces or recesses s between similar pegs on the other roll, so as to cause local stretching of the sheeting as it passes through the rolls. The successive pairs of rolls may be driven at progressively' increasing peripheral speeds to veffect longitudinal stretching as well as local stretching.

Cllr theory is that the mechanical working of sheetings ysuch as described, while wet, after once having been dried, results in a physical change in the form of the rubber present therein. The amount of this working is far too small to be analogous to the breaking down produced on the rollsof a rubber mill. The best analogy seems to be the eifect produced when a fresh coagulum of rubber is gently lmea'ded. For instance, it is Well known that the addition of dilute acid to latex causes the precipitation of a very soft and fiabby coherent curd. If this is worked between the fingers for a few minutes, it becomes tough, leathery, and elastic. It is possible that a similar action occurs when a Wet rubber-impregnated sheet is gently Worked as hereinbefore described.

'The method of the invention and various ways in which it may be ap lied in practice having been thus described, 1t should be evident to those skilled in the art that various changes and modifications might be resorted to without departing from the spirit or scope of inventionas defined in the appended claims.

What We claim is l. Amethod which comprises wetting dry,

rubber-impregnated, librous sheet material lli:

weave@ persed rubber of the character of latex, progressively engaging the web at spaced regions laterally thereof while subjecting it to stretching longitudinally throughout its body portion between said regions, and redrying the stretched web.

4. A method which comprises wetting throughout a predried continuous web of felted cellulose fibers impregnated with water-dispersed rubber of the character of latex; passing the wet web progressively through the nips of a series of pair of rotating rolls, the rolls of each pair of said series being rotated at the same peripheral speed but greater than that of a preceding pair, to effect a longitudinal stretching of the web throughout its body portion; and redrying the stretched web.

In testimony whereof we have afxed our signatures.

ROGER B. HILL JOHN A. FOGARTY. 

